The invention is directed to a novel safety razor construction and more particularly directed to a shaving unit or razor blade assembly having a movable cap.
Since the introduction of the safety razor, the shaving unit or blade assembly has consisted principally of three members, namely, a blade, a guard bar and seat combination connected, or connectable, to a handle, and a cap. The function of the guard bar/seat and the cap is to properly locate and hold the blade in the proper location for cutting hair in controlled contact with the skin. Generally these elements have been manufactured as separate components which, when removably attached or fixedly attached to the handle, combine to maintain desired geometry in relationship to these elements during the act of shaving.
Of more recent development is the bonded cartridge or razor blade assembly in which the seat, cap and blade are permanently and rigidly bonded together to achieve and maintain a desired shaving geometry and fixed relationship of the parts. In this arrangement, the cartridge is adapted to be coupled as a complete and unitary assembly to the handle. This type of configuration is exemplified and disclosed in U.S. Pat. No. 3,783,510, which employs a tandem or twin blade assembly with a spacer therebetween permanently and rigidly bonded to a cap and platform member, the platform member or seat having an integral guard bar and coupling members for attachment to the handle.
Similarly, so-called disposable razors are known which employ all or most of the features of a bonded cartridge blade assembly and which also incorporate the handle with the blade assembly in a non-detachable manner, as by integrally molding it with the seat.
Except for those razors in which a blade is loaded or fixed therein by the user just prior to shaving, it is generally desirable to provide some form of protective cover for blade assemblies to prevent contact of the blade edge with various external elements which might either be hard enough to do harm to the blade edge or otherwise be sufficiently soft to be cut, as the skin of a user or handler. In the instance of the aforementioned bonded cartridges, they have typically been marketed in multicompartmented dispensers, such as disclosed in the aforementioned U.S. Pat. No. 3,783,510, which isolate the blade edges until they are ready for use. The so-called disposable razors have also been provided with protective covers which normally take the form of a singly-compartmented cover which removably fits over at least the cap and blade portions of the razor.
A disposable safety razor recently introduced in Japan by the Kai Safety Razor Company, Ltd. under the identification MC2-200 does provide certain movable elements which cooperate to either expose the blade edge for shaving or relatively cover it for safe handling. That capability is afforded by providing an integrally formed seat member and handle, a blade(s) fixed to a movable platform which includes an integral guard bar member, and a cap which snap-locks with the seat member. A cam member is rotatably connected to the seat member and in camming engagement with the blade platform so as to move the platform, guard bar and blades(s) back and forth (in and out) relative to the cap and seat member when manually rotated. However, it will be appreciated that such a mechansim makes a relatively complex, and presumably costly, structure of an otherwise simple, and presumably less expensive, disposable razor.
Also, there have been a variety of efforts to provide blade assemblies in which the desired geometry of the blade relative to the cap and/or seat and guard elements may be varied. The geometrical parameters which are believed to play the greatest role in shaving comprise blade exposure, blade tangent angle, and span angle. These terms are defined as follows: The blade exposure is the normal distance the blade edge extends beyond or back from a plane tangent to the cap and the guard bar; the blade tangent angle is the angle formed between a plane tangent to the blade edge and the guard bar and a second plane bisecting the blade edge; and the span angle is the distance measured between the blade edge and a tangent point on the guard bar. One such device is described in U.S. Pat. No. 3,500,539 wherein a transversely arrayed guard bar is connected to the blade platform by a yieldable web structure. In yet another example, that of U.S. Pat. No. 4,063,354, there is described a shaving unit in which the guard element and/or the cap element may be resiliently moved relative to the blade and seat assembly in response to shaving forces. These blade assemblies, however, are also relatively complex and do not address the problem of providing a protective cover for the blade edges.
Accordingly, it is a principal object of the present invention to provide an improved razor blade assembly in which the cap element may additionally serve as a protective blade cover. Included within this object is the provision of such dual purpose cap in a razor blade assembly which is relatively simple and inexpensive to manufacture and assemble.
It is a further object of the invention to provide a razor blade assembly having a movable cover cap which provides stability to the blade therebeneath.